An apparatus provided for monitoring thumb twitch includes a support structure constructed and arranged to support at least a hand of a patient. A pressurized biasing member is operatively associated with the support structure and located to contact the patient's thumb with the biasing member disposed between the thumb and support structure when the patient's hand is placed in the support structure. A pressure sensor is associated with the biasing member to generate an electrical signal corresponding to pressure exerted by the biasing member. A method of monitoring thumb twitch is also provided.
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5. An apparatus for monitoring thumb twitch, the apparatus comprising
a support structure constructed and arranged to support at least a hand of a patient, a pressurized biasing member operatively associated with the support structure and located to contact the patient's thumb with the biasing member disposed between the thumb and support structure when the patient's hand is placed in the support structure, and a pressure sensor associated with the biasing member to generate an electrical signal corresponding to pressure exerted by the biasing member, wherein the biasing member is a balloon pressurized with fluid.
14. An apparatus for monitoring thumb twitch, the apparatus comprising
a support structure constructed and arranged to support at least a hand of a patient, a pressurized biasing member operatively associated with the support structure and located to contact the patient's thumb with the biasing member disposed between the thumb and support structure when the patient's hand is placed in the support structure, and a pressure sensor associated with the biasing member to generate an electrical signal corresponding to pressure exerted by the biasing member, wherein a tube structure fluidly couples the biasing member to the pressure sensor.
1. A method of monitoring thumb twitch using an apparatus having a support structure configured for supporting at least a hand of a patient, the apparatus including a pressurized biasing member operatively associated with the support structure and located to contact the patient's thumb when the patient's hand is placed in the support structure, and a sensor associated with the biasing member, the method including the steps of:
placing the patient's hand in the support structure such that the thumb of the patient contacts the biasing member with the biasing member being disposed between the thumb and the support structure, stimulating the ulnar nerve to cause the thumb to adduct and press the biasing member against the support structure with the sensor generating an electrical signal in response to the pressure exerted by the biasing member, and monitoring the electrical signal, wherein the biasing member is a balloon and the method includes injecting air into the balloon to a pressure of 15-20 mm Hg prior to the stimulating step.
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This invention relates to evaluating neuromuscular blockade by monitoring a thumb twitch response to train-of-four (TOF) nerve stimulation.
The use of muscle relaxants is an integral part of anesthetic management in present day practice. Currently, neuromuscular blockade is evaluated by determining the muscular reaction to train-of-four (TOF) nerve stimulation. There is equipment available for mechanical measurement of muscular response, such as the use of EMG, force displacement transducers, and most recently, the use of an acceleration transducer-based system of neuromuscular monitoring. These types of equipment, however, take time to set up and adjust, and are expensive. Because of these limitations, the daily routine use of such mechanical monitoring equipment is impractical. The evaluation of neuromuscular blockade therefore, at present, relies on the response, such as thumb twitch, to the TOF nerve stimulation which is evaluated either visually or manually (tactile).
Tactile or visual evaluation of neuromuscular blockade is subjective and involves uncertainty especially in the recovery phase. Furthermore, in certain surgical procedures when both hands are inaccessible, evaluation of the TOF by ulnar nerve stimulation is difficult or impossible. In such situations, muscle relaxants are given without clear objective criteria.
Accordingly, there is a need to provide a simple and inexpensive way of measuring the thumb twitch response to TOF stimulation during anesthesia.
An object of the present invention is to fulfill the need referred to above. This objective is obtained by providing a simple method for monitoring of the thumb twitch. The method uses an apparatus having a support structure configured for supporting at least a hand of a patient. The apparatus includes a pressurized biasing member operatively associated with the support structure and located to contact the patient's thumb when the patient's hand is placed in the support structure. A sensor is associated with the biasing member. The method includes placing the patient's hand in the support structure such that the thumb of the patient contacts the biasing member with the biasing member being disposed between the thumb and the support structure. The ulnar nerve is stimulated to cause the thumb to adduct and press the biasing member against the support structure with the sensor generating an electrical signal in response to the pressure exerted by the biasing member. The electrical signal is monitored.
In accordance with another aspect of the invention, an apparatus for monitoring thumb twitch includes a support structure constructed and arranged to support at least a hand of a patient. A pressurized biasing member is operatively associated with the support structure and located to contact the patient's thumb with the biasing member disposed between the thumb and support structure when the patient's hand is placed in the support structure. A pressure sensor is associated with the biasing member to generate an electrical signal corresponding to pressure exerted by the biasing member.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
Referring to
The apparatus 10 includes a biasing member 14 operatively associated with the support structure 12. In the illustrated embodiment, the biasing member 14 is in the form of a elongated balloon, preferably sized 6×2 cm and having 8 ml capacity, fixed on the support structure 12 at a location corresponding to a thumb and thenar eminence location. The support structure 12 can be made to fit either the left or right forearm and hand.
A connecting tubing structure 16 fluidly couples the balloon 14 through a conventional three-way stopcock connector 18 to a pressure transducer or sensor 20. The pressure sensor 20 can be any conventional physiological pressure transducer or sensor that can be used to measure arterial or venous pressure. In the illustrated embodiment, the pressure sensor 20 is a Transpac No. 46086-20 disposable transducer manufactured by Abbot Critical Care Systems.
In accordance with the invention, at least the patient's hand 15 is placed in the support structure 12 such that the thumb 21 of the patient contacts the biasing member 14, with the biasing member being disposed between the thumb and the support structure 12. In the embodiment of
Fluid, such as air or saline, is injected into stopcock connector 18 through port 28 so as to pressurize the biasing member 14 to a pressure of about 15-20 mm Hg. The ulnar nerve over the ulnar groove at the elbow is stimulated to elicit a strong thumb adduction (because of stimulation of the flexor carpi ulnaris muscle), causing the thumb to press the biasing member 14 against the support structure 12. The pressure exerted by the biasing member 14 is transmitted to the pressure sensor 20 with the pressure sensor 20 generating an electrical signal in response to the exerted pressure. The pressure sensor 20 includes a connector 19 which is constructed and arranged to be connected to a conventional vital signs monitoring device (not shown) to display the electrical signal.
As shown in
The advantages of the apparatus and method are:
1. The apparatus is simple and easy to apply.
2. The apparatus is inexpensive and can be reused.
3. The apparatus utilizes an existing pressure channel of the monitor.
4. Once secured, the hand with the apparatus can be placed away from the anesthesiologist.
5. Remote monitoring is possible when both upper extremities are hidden under the surgical drapes and are inaccessible to the anesthesiologist.
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
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